AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Using Spectral Analysis and Fluorescence Lifetime Imaging Microscopy (FLIM) to Discriminate between Grass and Non-grass Pollen
JOHN SODEAU, David O'Connor, David Healy, Daniela Iacopino, Pierre Lovera, University College Cork
Abstract Number: 21 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract A study has been performed that provides the first FLIM results for specific in situ biochemical components of individual pollen. The data obtained show that such measurements can, at least, provide a basis for discrimination between airborne grass and non-grass pollen. Relevant spectral data were obtained from the absorption, fluorescence and excited state lifetime measurements of three grass pollen and three non-grass pollen (Anthoxanthum odoratum (AO) Dactylis glomerata (DG) Fagus sylvatica (FS) plus Lolium perenne (LP), Quercus robur (QR), Quercus ilex (QI)).
Using excitation at 402 nm, the most striking differential FLIM spectral observation was found for the individual grass pollen, all of which featured a band with wavelength maxima at 675 nm and 725 nm. The feature is readily attributable to chlorophyll-a; these bands are absent from the non-grass counterpart spectra. The fluorescence lifetime experiments provided unambiguous evidence to show that the chlorophyll-a was located in a region that resembled a “free” solution environment. Furthermore the measurements are consistent with the fluorescence signals also originating from one further source: NAD(P)H bound to a protein. Such a result may be expected because of the photosynthetic origin of NAD(P)H but it has not been shown before for grass pollen. In contrast, the lifetime results obtained for the non-grass pollen can be interpreted purely in terms of the presence of the metabolite, flavin adenine dinucleotide (FAD), likely bound within a cell.
The work is relevant to the study of atmospheric dispersions of Primary Biological Aerosol Particles (PBAP) because the discriminatory lifetime fluorescence parameters obtained might be utilized for their real-time detection if suitable technical adaptions to current instrumentation can be made.